Biplate metal



M. M. AUSTIN BIPLATE METAL Jgn. 16, 1934.

Filed Oct. 3l, 1930 www 204 ,ZZ/ Z Patented Jan. 16, 1934 I y l 943853;

UNITED STATES PATENT OFFICE BIPLATE Miner M. Austin, Waukegan, Ill., assignor to Fansteel Products Company, Inc., North Chicago, ill., a corporation of New York Application October 31, 1930. Serial No. 492,498

4 Claims. (Cl. 29l81) .5

This invention relates in general to loi-plate tantalum and columbium at high temperatures metal, and while it pertains to bi-platemetal or without the necessity of providing a vacuum or roll plate such as is used in the manufacture of inert atmosphere. jewelry, the invention has more particular refer- Another object of the present invention is to 5 ence to a rare metal such as tantaium coated provide useful and novel articles of manufacture 60 on an alloy of copper and a method of producing having the conductivity, strength and physical such a bi-plate metal.v 7 properties of copper alloy with a non-corrosive .While 8 iii-Plate metal 0011191451118 a rare meta! plate which has the physical, electrical and chemisuch as tantalurn or columbium and a base metal cal characteristics of rare metals such as tantalum 10 is desirable for use in the manufacture of rare and cglumbium, 65 mGIICISS it iS 110i Practical t@ Sweat 01' t0 Still another object of this invention is the 616617101713110 antlm 01' COlumbiiim Plate t0 a provision of a relatively inexpensive alloy and a base metal plate in the manner now common in substantially integral rare metal plate formed the case of gold and silver rolled plate, for the thereon for the manufacture of rare metal artireason, among others, that the ordinary solder cles, whereby to effect a saving in the cost of such 70 ing, brazlng, and welding compounds and base articles. 1 metals will not wet the rare metal. Such a Other objects will be apparent as the detailed product of tantalum or columbiuxn effects a savdescription of the invention proceeds.

lng in the quantity of rare metal required to form The accompanying drawing shows a preferred 2o the article, and therefore, effects' a saving in the embodiment of the invention and similar parts 76 cost of the article. are' referred to by like reference characters The present invention contemplates dipping throughout the several views. clean tantalum into a molten copper alloy of Fig. 1 is a horizontal section through the electric aluminum, nickel, or any other metal having a furnace-and molten alloy crucible.

solvent action on the tantalum. The dipping Fig. 2 is a perspective view of the tantalum 30 forms an adherent film or slab of the alloy on the coated with an alloy film. surface of the tantalum, the film or slab protect- Fig. 3 is a horizontal section through the graphing the tantalum surface, preventing gas absorpite mold in which the molten alloy is being poured. tion by the tantalum and oxidation thereof when Fig. 4 is a perspective of the strip comprising a heatedin air, and providing abase for the attachtantalum plate having an alloy film on one side 85 ment of additional metal by soldering or brazing and an alloy base on the other. in a known manner. The copper alloys men- Fig. 5 is a diagrammatic representation of the tioned above are here preferred because of their rolling process. mechanical strength and resistance to corrosion. Fig. 6 is a diagrammatic representation of acid When the lm or slab has been formed on the treating tank; and 90 tantalum, it is possible to proceed asin the prepa- Fie. 7 iS an embodiment in Which a tantalum ration of rolled plate; that is, to attach a thick plated wire is formed by my improved process. metal backing to the film or slab by means of Briefly the invention contemplates dipping a hard solder. This backing may then be annealed strip of pure tantalum metal into a. super-heated 4o in air te aid in the roumg process, the mm on the bath of aIuminum copper or nickel copper alloy 95 opposite surface of the tantalum protecting the 0r into such bath having a layer 0f fused D0- tantalum as above described, tassium tantalum fluoride covering the alloy. An important object of the invention is there- This coated strip is then putin a sand or graphite fore to provide a metal plate, sheet, tube, or wire mold and a quantity of the alloy is poured on one of ordinary metals with an integral plate of a side so that the strip is formed having a film of the 100 rare metal such as tantalum and columbium withalloy on one side of the tantalum and a very thick out'the use of soldering compositions. base on the other side of the tantalum. 'I'his Another important object of the invention is to strip may be rolled into very thin sheets, and the Unite B rare metal With SI1-Ordinary metal t0 adherence between the tantalum and the alloy provide a perfect joint and to eliminate bubbles is substantially perfect, due probably to the fact 105 or iiaws in the joint thus provided, whereby t0 that the aluminum or the nlckelin the respective obtain perfect adhesion between the rare metal alloys exerts a powerful solvent action on the and the ordinary metal. tantalum.

A further objectof the invention is to provide a For accomplishing the foregoing objects. a novel means for treating rare metal plates such as graphite crucible 10 is placed in an electric fur- 11 nace ll, as shown in l. This furnace may be 'oriey characterized as an alundum cylinder 12 having alundum base i3 around which is wound a molybdenum coil i4, the terminals of which are connected by conductors 15 and 16 to a source of supply. Magnesio. or other refractory insulating material i8 insulates the heated elements above described from the supporting frame or containerl. No novelty is claimed in the furnace per se and it will not therefore be described in detail.

The graphite crucible is nearly filled with an alloy 2o preferably of copper and nickel or copper and aluminum. nickel content the first alloy is preferably about to l0 percent, and the in the second is from 2 to l@ percent, it being understood, however, that other percentages may be used without departing from the spirit or scope of the invention. While copper alloys are described, it will be understood that the invention'contemplates the use of iron, gold, lead, platinum, aluminum, tin, and other metals. The coating or backing alloy may be characterized in general as a base metal having the desired physical and chemical properties alloyed with a solvent metal which will giv`e perfect adhesion with tantalum.

When the alloy 20 is molten and has become slightly superheated, the temperature naturally varying with the alloy used, a strip 21 of tantalum is dipped into this molten mass to form a nlm on the tantalum. The strip is allowed to remain for about seconds, after which it is removed from the molten alloy. This dipping forms an extremely adherent film of the alloy over the entire surface of the tantalum. 'I'he strip of tantalum coatedwith the alloy film is illustrated diagrammatically in Fig. 2.

A tantalum oxide film on the surface of the tantalum is sometimes responsible for the difficulties encountered in joining tantalum to a base metal. Where desired, therefore, this invention contemplatescovering the molten alloy with a layer of a solvent for the oxides of tantalum. A double salt of fused potassium tantalum fluoride has been found to dissolve the tantalum oxides which may have formed on the tantalum and may be used to cover the molten alloy so that the vtantalum is immersed first in the upper layer of fluoride and then in the alloy therebeneath.

This strip is placed in a sand or graphite mold 22 and a relatively large amount of the alloy is poured on the strip in the mold by a crucible or ladle 23 or the coated tantalum is fixed to a thick metal backing by means of silver solder. The film 20A on the bottom of the plate remains unchanged, the film 20B on the top of the plate fuses with the added alloy 20C and becomes an integral part of this base metal. The strip of tantalum plate secured to the copper alloy base in this manner is diagrammatically illustrated in Fig. 4.

This strip may be rolled to any desired thickness by conventional rollers diagrammatically illustrated at 24 in Fig. 5. While the malleability, hardness, toughness, etc. of the tantalum differs from those qualities of the base metal, the adhesion between these two metals is so great that the tantalum is reduced in thickness in the rolling process almost in proportion to the base metal. A bi-plate metal formed as described above, by continued rolling produces plates in which the tantalum is of almost microscopic thickness, and there will be no rupture between the tantalum and the base metal alloy during the entire rolling process. During the process the plate or stripmay be annealed by heating it in the atmosphere, the alloy film effectively insulatng the tantalum from atmospheric oxygen.

The nai step of my process consists in removing the film of alloy 20A from the tantalum plate ater it has been rolled to the required thickness. This film erremely may be removed by dipping tentaient a bath of sulphuric 26 or any other suitable solvent contained in a tank or. receptacle 27, in Fig. tantalum being unattacised by practically alil solvents.

By dipping a rare metal into a molten bath as described above, a coating or film of pure gold has been formed on the tantalum, and copper, silver, or lead mixed with aluminum, beryllium, or a. metal of the iron group, such as nickel, when treated as described form an adherent coating on tantalum. Magnesium, calcium, silicon, or other vigorous reducing agents may be substituted for beryllium or aluminum.

Other metals and alloys suitable for coating rare metals are gold, cobalt and iron, cobalt and copper, and lead and aluminum. Instead of making fiat plates of base metal alloy plated with tantalum, the molten alloy may be poured in a tantalum cylinder which has' been dipped to form an alloy film as above described. This cylinder may then be swaged and drawn into a wire which will be in effect a base metal alloy core 28 surrounded by a tantalum plate 29, as shown in Fig. 7.

While a preferred embodiment of the invention has been described, it will be understood that the invention is not limited to the details set forth except as defined by the appended claims.

I claim:

i. A bi-plate metal comprising a tantalum plate, a copper alloy film thereon having from 5 r10%-nickel, and a base metal adhering to said 2. A bi-plate metal comprising tantalum, a copper alloy nlm adhering thereto and containing from 2 to 10% aluminum and a base metal adhering to said film.

3. A bi-plate article of manufacture comprising a tantalum plate, an alloy film of copper and a metal of the iron group adhering to said plate. and a base metal adhering to said film on said tantalum plate.

` 4. A bi-metal article of manufacture comprising a tantalum plate, a base metal film autogenously attached thereto and protecting said plate aganst the deleterious influences of the atmosphere, and a base metal plate autogenously attached to said film.

MINER M. AUSTIN.

.rif 

